Digestive Physiology In Humans Essay

3389 words - 14 pages

I. Introduction
The human digestive system consists of organs from the gastrointestinal tract, which is a tube that goes from the mouth to the anus. Either end of the mouth and the anus contain a lumen, which is open on each side for the external environment. Everything inside the lumen is considered to be external to the body. The organs that make up the GI tract consist of the mouth, stomach, pharynx, esophagus, large intestine, small intestine, and the anus. The human digestive system also consists of other organs that help with digestion, such as the salivary glands, teeth, liver, tongue, gallbladder, and the pancreas(Allen, Harper 2009).. The digestive system aids in ingesting food, secreting juices, moving and mixing food, breaking down food into absorbable, tiny molecules, absorbing digestive substances and molecules throughout the GI tract wall and inside the body, discharging through the anus (Tortora 2012).
There are two kinds of digestions, mechanical, and chemical digestions. Mechanical digestion is the breaking down of food into smaller pieces. It starts off in the mouth, and goes through the stomach and the small intestine. In the mouth, masticating or chewing occurs, which mechanically breaks down the food and allows it to be swallowed and travelled to the stomach. As the food reaches the stomach, the mixing of food and digestive juices occurs in until the food reaches the small intestine (Allen, Harper 2009). The mixing of food and the digestive juices makes it easier for digestion to occur. Chemical digestion is the breakdown of large molecules by the use of enzymes to break down the bond between carbohydrates lipids, and proteins. Enzymes are large protein molecules and are used to break down or catabolize carbohydrates, lipids, and proteins because they are not able to be broken down in the gastrointestinal tract (Alexander, Mathie, and Peters 2011).
Starch is a carbohydrate that is digested to form disaccharides and monosaccharides by an enzyme called amylase. Lipids are macromolecules that are digested to form glycerol and fatty acids by an enzyme called lipase (Reitan 2011). Protease is used to digest peptides that form into amino acids. Enzymes are really important because without them, the breakdown of food would be really hard and slow and could even cause chemical digestion to not occur. In order to understand the Digestive Physiology lab that was conducted, it important to know what digestion is and how it occurs. Without knowing how enzymes work, it would be difficult to understand the objectives of this lab (Bovard, Fellner, Hartstone-Rose, Lambert, McKenney 2012).
In the lab that was conducted, the first experiment was testing the digestion of proteins. An enzyme called pepsin was used to digest the substrate albumin. Pepsin is a different kind of digestive enzyme because it requires an acidic environment where the pH is low. To test if the digestion of protein occurred, a Biuret reagent is...

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